Former Ukrainian Prime Minister Yulia Tymoshenko, already sentenced to seven years in prison for abuse of office, has been charged with tax evasion, theft and concealing foreign currency revenues, the State Tax Administration said on Friday.

The charges are linked to her activities as the head of gas trading firm, United Energy Systems of Ukraine, it said in a statement, a post she held in the 1990s.

Tymoshenko has denied all earlier charges against her and said her trial reflected a political vendetta waged by President Viktor Yanukovich, who narrowly beat her in a presidential vote last year. Echoing her position, the European Union has warned Ukraine it may not sign planned bilateral deals on political association and free trade if Tymoshenko remains in jail.